When asked what plants need for photosynthesis, many students can correctly recall the reaction equation and state that plants require CO2, H2O, and light. Many students, however, do not understand that these reactants are the raw materials plants use to make sugars and instead believe that they are food for plants. Moreover, when questioned further, students often voice the idea that plants get their food from the soil (Kestler 2014). This is consistent with findings that fewer than half of current middle and high school students have a correct understanding of the process of photosynthesis (AAAS 2015). We developed this lesson to help students confront their misconceptions about photosynthesis and what constitutes food for plants. Photosynthesis is a complex process that requires a unit of instruction including multiple student experiences. Therefore, we use this lesson as an introduction to the unit on Matter and Energy in Organisms and Ecosystems so that students develop a better understanding of the reactants of photosynthesis.
Stevens, B., Rybczynski, S., & Herrington, D. (2016). Food and energy for all: Turning a demonstration into an inquiry activity. Science Scope, 40(4), 48-56.